J/A+A/707/A194 Filaments of Cygnus X (Li+, 2026)
A complete survey of filaments in Cygnus X.
Li Y., Qiu K.
<Astron. Astrophys. 707, A194 (2026)>
=2026A&A...707A.194L 2026A&A...707A.194L (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds
Keywords: stars: formation - ISM: clouds - HII regions - ISM: magnetic fields -
ISM: molecules - ISM: structure
Abstract:
Filamentary gas structures are widely observed in molecular clouds,
and are suggested to play a key role in the star formation processes.
However, existing observations of molecular filaments are still biased
to case studies and small samples and there is a lack of large sample
study from a single giant molecular cloud.
We aim to carry out a complete census of filaments in Cygnus X, and
obtain their physical properties, relations with dense cores, magnetic
field (B-field) and HII regions.
We extract 2633 filaments and 6551 cores from the column density map
of Cygnus X, using the most updated getsf algorithm. We then
investigate the mass functions for the cores on and out of the
filaments, compare the orientations of the filaments with that of the
B-field obtained with the Planck data, derive the radial column
density profiles of the filaments close to HII regions, and calculate
the distances between the identified young stellar objects and
filament spines. We also re-extract filaments at the resolution of the
Planck 353GHz dust emission map to study their relationship with the
B-field.
The filaments in Cygnus X have a typical width of 0.5pc. More than
93% of high-mass cores (≥20MSsun) are located on filaments. The
core mass function constructed from the cores on the filaments (onCMF)
shows a power-law in the high-mass end (>10MSsun) with a slope of
-2.30, whereas the high-mass end of the CMF derived from the cores
outside the filaments (outCMF) has a much steeper power-law
distribution with a slope of -2.83. The core mass corresponding to
the peak of onCMF is much less than the Bonner-Ebert mass but that
corresponding to the peak of outCMF is well comparable to the
Bonner-Ebert mass. Filaments re-extracted from the column density map
smoothed to an angular resolution identical to the Planck 353GHz map
are mostly perpendicular to the B-field, except that those of lowest
column densities are parallel to the B-field. The transition from
parallel to perpendicular occurs at a column density equivalent to
AV=10mag. Most prominent filamentary gas structures and high-mass
cores appear to be preferentially located along the boundaries of HII
regions or at the intersections of multiple HII regions. The filaments
close to the HII region boundaries show a steeper column density
profile on the side toward the HII region compared to that on the
opposite side.
The formation of more massive cores has a stronger dependence on
filaments, and the latter may provide a mass reservoir for the former
to grow in mass via accretion. The B-field plays a crucial role in
filament formation, and the type O mode where filaments form at the
tip of converging flows along an oblique MHD shock front may be
prevalent in Cygnus X. In this context, expanding HII regions in the
complex induces shocks which compress the surrounding gas, creating
inhomogeneity and dense clumps, and forming filaments. The global
picture of filaments, cores, and star formation in Cygnus X is
apparently consistent with the bubble-filament paradigm proposed in
the literature.
Description:
Physical parameters of the filaments and cores extracted with getsf.
Objects:
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RA (2000) DE Designation(s)
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20 30 04.79 +40 51 36.0 Cygnus X = 4FGL J2028.6+4110e
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 31 6551 Physical parameters of the cores
list.dat 75 1 Informations on fits image
fits/* . 1 fits image
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See also:
J/A+A/476/1243 : Millimeter continuum mapping of Cygnus X (Motte+, 2007)
J/A+A/527/A135 : Gas dynamics in Massive Dense Cores in Cygnus-X
(Csengeri+, 2011)
J/ApJS/241/1 : Surveys of clumps + cores in Cygnus X. I. ∼0.1pc MDCs
(Cao+, 2019)
J/ApJ/927/185 : Surveys of clumps + cores in Cygnus X. II. VLA obs.
(Wang+, 2022)
J/A+A/664/A88 : LOFAR 148MHz Cygnus X region image (Emig+, 2022)
J/ApJ/883/156 : Nobeyama 45m Cygnus-X CO. II. C180 clumps (Takekoshi+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 F6.2 deg RAdeg Right Ascension (J2000)
8- 12 F5.2 deg DEdeg Declination (J2000)
14- 19 F6.2 Msun CoreMass Core mass
21- 24 F4.2 pc Maj Major axis
26- 29 F4.2 pc Min Minor axis
31 I1 --- Flag [0/1] Filament (1=on, 0=off)
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20 I1 arcsec/pix scale Scale of the image
22- 25 I4 --- Nx Number of pixels along X-axis
27- 30 I4 --- Ny Number of pixels along Y-axis
32- 37 I6 Kibyte size Size of FITS file
39- 60 A22 --- FileName Name of FITS file, in subdirectory fits
62- 75 A14 --- Title Title of the FITS file
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Acknowledgements:
Yingxi Li, starryyousei(at)gmail.com
(End) Patricia Vannier [CDS] 14-Jan-2026